A transformer explosion at Eskom’s coal-fired 3.6-GW Matla Energy Station in Mpumalanga, South Africa, on Dec. 12 injured 9 staff, together with one critically. The incident, brought on by a ruptured high-pressure steam pipe, has underscored challenges confronted by Eskom’s producing fleet, even because the state-owned maintains its suspension of load-shedding.
The incident, reported at 5 p.m. on Thursday, stemmed from the rupture of a high-pressure steam metal pipe above the Unit 6 transformer. “The incident resulted in a loud bang and a lack of energy provide to the Unit 6 space,” Eskom reported on Friday morning, Dec.13. “Vital quantities of mud, mixed with the lack of energy, prevented a fuller evaluation till the primary mild this morning.”
An investigation is underway, Eskom mentioned. Technical groups stay onsite to evaluate the extent of the harm, the scope of labor, and the time required for repairs and restoration. “At this stage, there is no such thing as a proof of sabotage,” it mentioned, citing a preliminary investigation.
“We now start a disciplined investigation and the painstaking work required to develop a radical, disciplined understanding of the incident that may lead us to have the ability to plan when the unit may be returned to service,” mentioned Eskom Group Govt for Era Bheki Nxumalo.
3.6-GW Matla Has Lengthy Been a Workhorse
The Matla Energy Station is one among Eskom’s 15 coal-fired energy crops but it surely performs an vital function in making certain South Africa’s reliability, given its proximity to Mpumalanga’s coal-mining area. Like most of Eskom’s 38-GW coal fleet, the station’s age exceeds 40 years outdated. Constructed between 1976 and 1983, the Matla (a Sotho phrase which means “power”) station contains six models, every with a capability of 600 MW.
These models make the most of 2-pole, 3,000 r/min synchronous turbines rated at 688.9 MVA and 20 kV, with water-cooled stators and hydrogen-cooled rotors. Energy from every generator is transferred to the nationwide grid through oil-cooled 700 MVA generator transformers, two of which step up voltage from 20 kV to 400 kV, whereas the remaining 4 step up voltage to 275 kV. Transformers are sometimes put in at energy stations to extend the voltage of energy to a degree appropriate for transmission over lengthy distances.
The ability plant was notably one of many first on the earth with a concrete boiler home superstructure, owing partly to a worldwide metal scarcity when it was constructed. Nonetheless, based on a Nationwide Treasury–commissioned evaluation of Eskom’s coal-fired energy crops launched in March 2024, the station was designed with an working lifespan of 30 years. Whereas its continued operation is envisioned one other 20 years, a deliberate rehabilitation mid-life (2010 to 2013) didn’t happen, although some technical upgrades had been carried out.
“Up to now, Matla was a dependable and persistently well-performing station, but it surely has been in regular decline since 2007. This decline began accelerating in 2018, as a result of deteriorating coal high quality and lack of satisfactory upkeep. From among the finest working crops within the fleet in 2017 (82.2% power availability issue [EAF]), it reached 53.3% EAF by the top of FY2022/2023,” the report says.
Pressing Technical and Operational Points
In accordance with the report, which was performed by a world consortium led by technical power plant operator affiliation vgbe, Matla faces a number of important technical and operational challenges that require pressing consideration. Poor coal high quality, exacerbated by delays in securing coal that meets design specs, has contributed to frequent boiler tube failures, lowered mill reliability, and elevated pressure on ash dealing with programs and electrostatic precipitators.
Deferred upkeep has additional degraded key elements, together with steam generators and feeder programs, whereas emission management tools stays non-compliant with particulate matter (PM) requirements and requires upgrades to fulfill tightening SO₂ and NOx rules by 2025. Regardless of some latest enhancements, together with cooling tower upgrades and catch-up on outages, these points have led to derating of models and a considerable decline in efficiency, jeopardizing the plant’s reliability and long-term viability. The 600-MW Matla Unit 6, notably, suffered a hearth incident in December 2022 because of a gasoline oil leak, leading to harm to electrical cables.
The station’s transformers have additionally confronted reliability considerations as a result of growing older infrastructure and deferred upkeep. The report highlights the necessity to substitute turbine governors, safe spares for medium and low-voltage switchgear, and procure reserve generator rotors and transformers for Models 3–6 to make sure operational stability and mitigate dangers of additional failures.
The report suggests these points mirror these at a number of Eskom coal crops. Eskom, in the meantime, additionally has a historical past of transformer explosions. On Dec. 29, 2021, a transformer explosion occurred on Unit 8 of the 1.6 GW Camden Energy Station as a result of an inside fault. Whereas the fireplace was contained and no accidents had been reported, a 200-MW unit was taken offline for investigation to evaluate the harm and decide its return to service.
Equally, on Sept. 11, 2021, a generator transformer at Kendal Energy Station’s Unit 1 caught hearth, inflicting the unit to journey. The hearth additionally broken cooling water system cables, resulting in the shutdown of Models 2 and three as a precaution. Whereas all personnel had been evacuated safely and the fireplace was contained, the incident required in depth investigation to determine the basis trigger. Models 2 and three had been subsequently returned to service later that week.
Eskom Has Staved Off Load Shedding for 260-Plus Days—A 5 12 months File
Eskom final week mentioned the outage at Matla 6 and a precautionary effort to deliver ahead a deliberate outage at Unit 5 just isn’t anticipated to vary its load-shedding outlook. Whereas nation, Africa’s most industrial nation, has lengthy grappled with frequent energy outages, it’s at the moment having fun with its longest stretch of uninterrupted energy provide in 5 years.
“In August, Eskom shared its Summer season Outlook, for the interval from 01 September 2024 to 31 March 2025 that predicted a possible state of affairs of a loadshedding-free summer time as a result of structural enhancements within the coal-fired fleet,” the corporate mentioned. “Eskom has immediately reached 261 consecutive days of load-shedding suspension,” it added.
“Matla is without doubt one of the six energy stations we prioritized within the Era Restoration Plan to finish loadshedding, and over the previous 18 months the staff have delivered an distinctive efficiency, attaining an Power Availability Issue (EAF) of 67.12%,” famous Eskom Group Chief Govt Dan Marokane.
“Primarily based on the structural enhancements within the technology efficiency of the coal-fired fleet, week by week Eskom is more and more in a position to soak up shocks to the system, regardless that the technology capability stays tight,” he mentioned.
Marokane steered a base case state of affairs for the summer time outlook signifies Eskom will dodge load shedding if unplanned outages keep at 13 GW or under. Eskom’s year-to-date common unplanned outages are at 11,875MW,” he famous.
—Sonal Patel is a POWER senior editor (@sonalcpatel, @POWERmagazine).
